The
objective of the game is to hold a simple majority of the major cities, the
supply centers (marked in the online version as black
and white squares) at the end of a Fall turn (each
year has a Spring and a Fall turn).

Aside from negotiating with other countries there are 4 things you can do:

Hold

Move

Support

Convoy

Hold basically means that you defend
the area you're already in. This is the equivalent of telling the unit to stay
where it is.

Move is a combination of two possible actions. First, and most simple,
you are moving from one territory to an unoccupied one. Second, and more
complicated, you are moving into a territory that your opponent either has an
army or navy in or will attempt to move into as well. If a unit moves into a
space already occupied by another unit then it fails in moving and remains
where it came from. If two units attempt to move into the same area they both
fail. They remain in the same spot they started in. If two enemy units attempt
to invade past each other (switch places) they both fail and remain where they
started.

Support is used to make a hold or move option stronger. If a holding
unit is attacked, then the supporting unit can help defend. If a moving unit
meets resistance, the supporting unit can help push them back. In order to
support, the unit must border the objective area (the country that's either
being moved into or defended).

If a unit is attacked while it's supporting, its support is taken away and it
attempts to defend. The attacker carries on with the attack minus the support.

Any nation can support any other nation. Support can not
be refused, but it does not force the supported unit to do anything.

Convoy is used by naval units on the water to transport armies to
different areas. If you have a chain of naval units convoying over multiple
spaces you can convoy the army through the chain in one turn. If you convoy
into an occupied space then the battle is treated like any other one. Other
nations can assist in a convoy.

Rules on combatWhile there are a lot of complexities to the system,
the basic idea is that each unit has a strength of 1. Every supporting unit
adds 1 to the total strength. So, for example, if one army with one unit
supporting it (total strength of 2) attacked one army without support (total
strength of 1) the defending unit would be driven out. That unit will retreat
to an unoccupied border country of the nation's choice. If there is no
unoccupied border then that unit is destroyed. As another example, if the army
driven out in the last example had support (a strength
of 2 to oppose the invaders strength of 2) then the invader would be driven
back.

If a unit is attacked while it's supporting, its support is taken away and it
attempts to defend. The attacker carries on with the attack minus the support.

Any nation can support any other nation. Support can not
be refused, but it does not force the supported unit to do anything.

Naval Movement
Moving armies is pretty simple. They can move into any bordering territory or
be convoyed across a body of water. However, there are a bunch of special
scenarios that apply to navies.

A navy can either be on a body of water or in a coastal country. If it is in a
coastal country it covers the entire coast line. However, there are some
special cases where they only cover part of the coast.

For example, look at Spain on the map. As you can see, it has a North coast and
a South coast. A unit that entered on the North coast can't, then, leave by the
South coast. However, the unit is still considered to defend the entire
country, even if attacked by a navy from the South.

If a navy is on a coast, it can move to any other coastal country it borders. A
navy can support land units and vice versa, but land units (obviously) can't
help with a battle in open water and naval units can't help with an inland
country.

Sweden and Denmark are considered bordering coastal countries. You can move
navies directly from one to the other other you can
pass between them.

Adding and removing unitsA country is allowed to have as many units as it has
major cities. That is why all the countries start with 3 units (except for
Russia which has 4). At the end of every Fall turn the
number of cities each nation has is counted. If it has more
units than it does cities then enough will need to be disbanded to make the
numbers even.

You are allowed to choose which units to disband. If you have more cities than
units then are allowed to place new units on any of your unoccupied 3 (or 4 if
you're Russia) starting cities. You are allowed to choose which of the two
types of units you wish to create if you are placing them in a coastal area. If
all your starting cities are occupied you will have to wait until the end of
next Fall to place new units.

If a country has taken some or all of your starting cities they can not be used to produce new units. In the scenario that
all of your starting cities are taken you will have to work with the units you
have left. If you retake the starting cities they are treated like they
normally would be.